The present invention relates to 7-beta- [2-(2-amino-4-thiazolyl)-2-methoxyiminoacetamido]-3-(2-amino-1,3,4-thiadia zolyl-5-thiomethyl) -3-cepheme-4-carboxylic acid represented by the formula(I): ##STR1## and the derivatives thereof and a pharmaceutical composition containing the same as an active ingredient. More in detail, the present invention relates to 7-beta- [2-(2-amino-4-thiazolyl)-2-methoxyiminoacetamido]-3-(2-amino-1,3,4-thiadia zolyl-5-thiomethyl)-3-cepheme-4-carboxylic acid, salts thereof and pivaloyloxymethyl ester thereof, and a pharmaceutical composition containing 7-beta- [2-(2-amino-4-thiazolyl)-2-methoxyiminoacetamido]-3-(2-amino-1,3,4-thiadia zolyl-5-thiomethyl)-3-cepheme-4-carboxylic acid, a pharmaceutically acceptable salt thereof or pivaloyloxymethyl ester thereof as an active ingredient.
Still more in detail, the pharmaceutical composition according to the present invention contains 7-beta- [2-(2-amino-4-thiazolyl) -2-methoxyiminoacetamido]-3-(2-amino-1,3,4-thiadiazolyl -5-thiomethyl)-3-cepheme-4-carboxylic acid which has a remarkably improved stability in blood of a living body while still retaining the antimicrobial activity of the so-called third generation antibiotics derived from cephalosporin by virtue of modifying 3-position of the so-called third antibiotics derived from cephalosporin by a 2-amino-1,3,4-thiazolyl-5-thiomethyl group, a pharmaceutically acceptable salt or pivaloyloxymethyl ester thereof as an active ingredient.
Cephalosporin antibiotics are broadly utilized at present because of their excellent anti-bacterial activity, however, although they have various merits of showing activity against both gram-positive and gram-negative bacteria in a broad range and of being stable to beta-lactamase, they have a serious demerit of being low in stability in blood of the host resulting in a short active life thereof in the host when administered thereto. As a result of the present inventors' studies for finding an antibiotic showing a cephalosporin-like activity without losing its activity even in the blood of the host, it has been found that 7-beta- [2-(2-amino-4-thiazolyl)-2-methoxyiminoacetamido]-3-(2-amino-1,3,4-thiadia zolyl-5-thiomethyl)-3-cepheme-4-carboxylic acid represented by the formula(I) and some derivatives thereof are effective in the above-mentioned sense, and the present inventors have attained the present invention.